The present invention relates to a method for decontamination of an enclosure, such as a hotel room, hospital ward, or laboratory. It finds particular application in the decontamination rooms containing soft furnishings and carpets, and will be described with particular reference thereto.
Large enclosures, such as rooms and buildings tend to become contaminated with a wide variety of microbial contaminants, including bacteria, molds, fungi, yeasts, and the like. These microorganisms thrive in damp spaces, such as behind walls, in plaster, under counters in bathroooms, and tend to be very difficult to eradicate. For example fungi are allergenic agents and are occasionally infectious in susceptible people. They pose problems in buildings where moisture control is poor or water intrusion is common. Fungi grow in moist environments and form dormant, resistant spores, which are disseminated in the air. These spores tend to contact surfaces favorable for spore germination and outgrowth. Some contaminants are brought into the room in the air, both through doorways, windows and the like as well as through ventilation systems. Contaminants are also carried into the room on the clothing or person by people using the room and from breathing, particularly when the room is one which is used for bathing or sleeping, such as a hotel room. Microorganisms are often left in the room when the person leaves. These microorganisms are often able to survive in carpets, drapes, wallpaper, furniture, on countertops, and the like. Some microbes cause a musty smell. Others can infect later users of the room. Additionally, there is a possibility that a room may be intentionally contaminated with pathogenic microorganisms, such as anthrax spores, smallpox virus, or the like. Some contaminants, such as tobacco smoke, body perfume, and medicinal odors are non-microbial.
In the case of hotel rooms, hospital wards, and the like, where the occupancy of a room is changing frequently, it is desirable to ensure that microorganisms and other decontaminants left behind by one occupant do not lead to contamination of a subsequent occupant. Hotel rooms, with time and use, develop odors.
Microbial decontamination of rooms and buildings has been achieved in the past using formaldehyde. However, formaldehyde is highly carcinogenic and powder residues must be recovered after the microbial decontamination process. Recovery of toxic gases from dilution air, leaking air, and the degassing of gas absorptive materials in the decontaminated room or building is difficult and time consuming. Further, care must be taken and monitors placed to ensure that the toxic gas does not escape into the surrounding areas.
Hydrogen peroxide vapor has been used for atmospheric pressure microbial decontamination of enclosures, isolated environments and their contents, and also such under vacuum conditions as a sterilizer of medical devices, and the like. Hydrogen peroxide vapor is a particularly useful sterilant for these purposes because it is effective at low temperatures. Vaporized hydrogen peroxide systems provide dry, rapid, low-temperature decontamination of sterilizer contents that are contaminated with microorganisms, including spore-forming bacteria. Keeping the temperature of the sterilizer near room temperature eliminates the potential for thermal degradation of associated equipment and items to be sterilized. In addition, hydrogen peroxide readily decomposes to water vapor and oxygen, which, of course, are not harmful to the humans including technicians and people nearby.
Typically, a slightly negative or positive pressure is used in the sterilizer. A solution of about 35% hydrogen peroxide in water is injected into a vaporizer as fine droplets or mist through injection nozzles. The droplets fall on a flat heated surface which heats the droplets to form the vapor, without breaking it down to water vapor and oxygen. A carrier gas is circulated over the heat transfer surface to absorb the peroxide vapor.
For optimally effective sterilization, the hydrogen peroxide is maintained in the vapor state. Sterilization efficiency and material compatibility are reduced by condensation. In the case of larger enclosures, difficulties arise in maintaining the conditions throughout the enclosure such that the hydrogen peroxide remains in the vapor state.
Hotel rooms are often cleaned with a bleach solution. However, bleach often leaves a chlorine odor. Plus, bleach is not color-safe on many fabrics, wall coverings, and carpets. Drapes are typically dry cleaned, an expensive and time consuming process. Shampooing rugs can leave them so damp that the room cannot be rented for a night—a significant revenue loss. Dry powder disinfectants applied to carpets leave the room with an odor of their own and tend to have a short-lived effect.
The present invention provides a new and improved system and method of decontaminating an enclosure which overcome the above-referenced problems and others.